Harry Enten argues that Obama’s falling approval rating “will likely be an albatross around the neck of the Democratic party”:
Obama’s approval rating can greatly affect the 2014 midterm elections and, to a lesser extent, the 2016 presidential election – and the historical odds of it recovering much seem to be slim.
In midterms, electorates often take out their frustration with the president on the their party’s congressional members. A poor presidential approval rating will only add to that frustration. A president likely needs an approval rating in the mid 60s, like Bill Clinton in 1998 and George W Bush in 2002, to avoid the curse of “midterm loss”.
In every non-wartime midterm election since 1938, simply knowing how many seats the president’s party controlled and the president’s approval rating goes a long way in determining how the midterm is going to shake out. Not counting 1974, because Richard Nixon resigned and Gerald Ford took his place, more than 75% of the variation between the seats won in the House by the president’s party in the midterm is explained by the two aforementioned variables.
(Chart from Pollster)